论文标题
原星磁盘中的分层和垂直剪切流型不稳定性
Stratified and vertically-shearing streaming instabilities in protoplanetary disks
论文作者
论文摘要
在正确的条件下，不完美耦合的灰尘和气体之间的流势是行星形成的强大机制，因为它可以将灰尘颗粒集中到引力塌陷点。以最简单的形式，可以通过分析代表代表原球磁盘中间平面的未分层磁盘模型的线性稳定性来捕获流媒体不稳定性。我们通过对原球磁盘中尘埃层进行垂直全球线性稳定性分析来扩展此类研究。我们发现分层灰尘层中不稳定的主要形式是由尘埃混合物旋转速度的垂直梯度驱动的，但也需要部分尘埃耦合。这些垂直剪切的流型不稳定性在轨道时标尺寸上生长，并以径向长度尺度出现$ \ sim10^{ - 3} h_ \ mathrm {g} $，其中$ h_ \ m m m m mathrm {g} $是本地压力尺度的高度。与尘埃和气体之间的相对径向漂移相关的经典流式不稳定性出现在径向长度尺度上$ \ sim10^{ - 2} h_ \ mathrm {g} $，但增长率比垂直剪切的流媒体不稳定性要小得多。包括气体粘度在内的稳定性很大，导致垂直延伸的干扰。我们简要讨论了垂直剪切的流媒体不稳定性对行星形成的潜在影响。
Under the right conditions, the streaming instability between imperfectly coupled dust and gas is a powerful mechanism for planetesimal formation as it can concentrate dust grains to the point of gravitational collapse. In its simplest form, the streaming instability can be captured by analyzing the linear stability of unstratified disk models, which represent the midplane of protoplanetary disks. We extend such studies by carrying out vertically-global linear stability analyses of dust layers in protoplanetary disks. We find the dominant form of instability in stratified dust layers is one driven by the vertical gradient in the rotation velocity of the dust-gas mixture, but also requires partial dust-gas coupling. These vertically-shearing streaming instabilities grow on orbital timescales and occur on radial length scales $\sim10^{-3}H_\mathrm{g}$, where $H_\mathrm{g}$ is the local pressure scale height. The classic streaming instability, associated with the relative radial drift between dust and gas, occur on radial length scales $\sim10^{-2}H_\mathrm{g}$, but have much smaller growth rates than vertically-shearing streaming instabilities. Including gas viscosity is strongly stabilizing and leads to vertically-elongated disturbances. We briefly discuss the potential effects of vertically-shearing streaming instabilities on planetesimal formation.
